Add support for throwing in async handlers.

lib/layer.js

@@ -65,6 +65,10 @@ Layer.prototype.handle_error = function handle_error(error, req, res, next) {
     return next(error)
   }
 
+  if (fn.constructor.name === 'AsyncFunction') {
+    return fn(error, req, res, next).catch(next)
+  }
+
   try {
     fn(error, req, res, next)
   } catch (err) {
@@ -89,6 +93,10 @@ Layer.prototype.handle_request = function handle(req, res, next) {
     return next()
   }
 
+  if (fn.constructor.name === 'AsyncFunction') {
+    return fn(req, res, next).catch(next)
+  }
+
   try {
     fn(req, res, next)
   } catch (err) {

test/route.js

@@ -10,6 +10,7 @@ var createServer = utils.createServer
 var request = utils.request
 var shouldHitHandle = utils.shouldHitHandle
 var shouldNotHitHandle = utils.shouldNotHitHandle
+var asyncFunctionsSupported = utils.asyncFunctionsSupported
 
 describe('Router', function () {
   describe('.route(path)', function () {
@@ -335,6 +336,59 @@ describe('Router', function () {
         .get('/foo')
         .expect(500, 'caught: oh, no!', done)
       })
+
+      if (asyncFunctionsSupported()) {
+
+        it('should handle errors thrown', function (done) {
+          var router = new Router()
+          var route = router.route('/foo')
+          var server = createServer(router)
+
+          route.all(new Function([],
+            "return async function createError(req, res, next) { throw new Error('boom!') }"
+          )())
+
+          route.all(helloWorld)
+
+          route.all(function handleError(err, req, res, next) {
+            res.statusCode = 500
+            res.end('caught: ' + err.message)
+          })
+
+          request(server)
+            .get('/foo')
+            .expect(500, 'caught: boom!', done)
+        })
+
+        it('should handle errors thrown in error handlers', function (done) {
+          var router = new Router()
+          var route = router.route('/foo')
+          var server = createServer(router)
+
+          route.all(function createError(req, res, next) {
+            throw new Error('boom!')
+          })
+
+          route.all(new Function([],
+            "return async function handleError(err, req, res, next) { throw new Error('oh, no!') }"
+          )())
+
+          route.all(function handleError(err, req, res, next) {
+            res.statusCode = 500
+            res.end('caught: ' + err.message)
+          })
+
+          request(server)
+            .get('/foo')
+            .expect(500, 'caught: oh, no!', done)
+        })
+
+
+
+      }
+
+
+
     })
 
     describe('next("route")', function () {

test/support/utils.js

@@ -12,6 +12,7 @@ exports.rawrequest = rawrequest
 exports.request = request
 exports.shouldHitHandle = shouldHitHandle
 exports.shouldNotHitHandle = shouldNotHitHandle
+exports.asyncFunctionsSupported = asyncFunctionsSupported
 
 function createHitHandle(num) {
   var name = 'x-fn-' + String(num)
@@ -120,3 +121,12 @@ function shouldNotHaveHeader(header) {
     assert.ok(!(header.toLowerCase() in res.headers), 'should not have header ' + header)
   }
 }
+
+function asyncFunctionsSupported() {
+  try {
+    new Function([],"return async function(){}")
+    return true
+  } catch(e) {
+    return false
+  }
+}